Auto-switching duplex module

ABSTRACT

A system and method (“utility”) for providing power to an electrically powered device from alternate, redundant power sources via a single power cord. The utility is operable to provide redundant power to an electrical device having a power cord terminating in a standard plug. The utility is operable to sense a loss of power quality from one power source, and to switch a connection to another power source in response to the loss. The utility may be configured to match the form factor of a standard (e.g., NEMA or other electrical standard) duplex receptacle unit. The utility may be incorporated into a standard outlet box or may plug into a standard outlet box.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. patent applicationSer. No. 12/531,231, entitled, “AUTO-SWITCHING DUPLEX MODULE,” filed onSep. 14, 2009, which is the U.S. National Stage of PCT ApplicationPCT/US2008/57144, entitled, “AUTOMATIC TRANSFER SWITCH MODULE,” filed onMar. 14, 2008, which claims priority from U.S. Provisional ApplicationNo. 60/894,848, entitled, “NEMA AUTO-SWITCHING DUPLEX MODULE,” filed onMar. 14, 2007, the contents of which are incorporated herein as if setforth in full.

BACKGROUND

It is often the case that data processing equipment and medical deviceshave only one power supply, and therefore, one power cord. These typesof equipment may often be employed in critical applications. Forexample, medical equipment may be used in situations where a person'slife may be dependent upon the continuing operation of the medicaldevice. Additionally, electronic data processing (EDP) equipment may beused in various systems where “downtime” may be extremely costly.Therefore, it is desirable to minimize the downtime of these devices.

One of the most significant causes of downtime for electronic equipmentis loss of power. This may occur due to human error, failure of acomponent in the device, or failure of a component in the power deliverypath that leads to the device. To provide for greater reliability,redundancy is often provided in these “mission-critical” applications byimplementing systems that greatly increase the complexity of theapplication. Further, this redundancy often comes at a high pricebecause each system generally will have a duplicate standby power supplyto provide power in the event of an interruption of power from the mainpower supply.

It is against this background that the auto-switching duplex module ofthe present invention has been developed.

SUMMARY

The present invention is directed to a system for providing power to anelectrically powered device—e.g., such as a critical network device,critical medical device, or other critical or non-critical device, fromalternate, redundant power sources via a single power cord. In thismanner, a higher degree of reliability can be achieved for conventionalelectrical devices having a single power cord. Moreover, suchreliability can be achieved by appropriately configuring conventionaloutlets without requiring additional power cords. The invention cantherefore be implemented simply and with minimal expense, thus enablinghigher reliability in many contexts.

In accordance with one aspect of the present invention, an apparatus isprovided for use in delivering power to a device having a power cordterminating in a standard plug. The apparatus includes a first standardreceptacle for receiving a standard plug, first and second terminalassemblies for interconnection to respective first and second powersources, and a switch for selectively interconnecting the first standardreceptacle to either the first terminal assembly or the second terminalassembly. In this manner, a single standard receptacle allows access toalternate power sources for enhanced reliability.

For example, the switch may operate automatically upon a loss of powerquality. That is, the switch may be operative for sensing a loss ofpower quality from one of the power sources and for switching aconnection of the receptacle in response to the loss of power quality.In addition, the apparatus may be configured to approximate the formfactor of a standard (e.g., NEMA or other electrical standard) duplexreceptacle unit. That is, the apparatus may be incorporated into astandard outlet box or may plug into a standard outlet box. In thisregard, the apparatus may include a second standard receptacle, whichmay also be switchable between the two power sources. In oneimplementation, the apparatus can be used in conjunction with anappropriately configured conventional power strip. For example, wherethe power strip provides outlets associated with first and second powersources, the apparatus may be plugged into the power strip to provide anauto-switching receptacle. Alternatively, the strip may be plugged intothe auto-switching receptacle such that the strip provides a number ofauto-switching receptacles to provide power to various electricaldevices.

The auto-switching module may be implemented in a small device suitablefor deployment in back of a rack-mounted device. For example, in theU.S. patent application Ser. No. 12/531,212 entitled, “AUTOMATICTRANSFER SWITCH MODULE,” which claims priority from PCT ApplicationPCT/US2008/57144 and, in turn, to U.S. Provisional Application No.60/894,842, all of which are incorporated herein by reference, a singlecord from a device is connected to two power strips, associated with twopower sources, by way of a “y” configured set of cords. Theauto-switching module can be used to provide auto-switching as betweenthe two sources (e.g., at the “y” intersection) so as to implementauto-switching at the device, rather than at the rack level, as may bedesired.

In accordance with another aspect of the present invention, a method foroperating an auto-switching receptacle is provided. The method involvesproviding a first standard receptacle for receiving a standard plugwhere, the receptacle is selectively associated with first and secondpower sources via a switch. An auto-switch device senses a loss of powerquality from one of the power sources and, responsive to the loss ofpower quality, the switch cycles to provide power from the other sourcevia the standard receptacle.

According to a still further aspect of the present invention, a methodfor using an auto-switching receptacle is provided. The method involvesproviding a module, including a module receptacle for receiving astandard plug, and a switch for switching a power source connection ofthe module receptacle. The method further involves connecting the moduleto first and second power sources and connecting a standard plug to themodule receptacle.

For example, the module may be connected to the first and second powersources by providing a standard duplex electrical outlet configured toprovide power from first and second power sources and connecting themodule to the standard outlet. Similarly, the module may be connected tothe first and second power sources by providing a power strip havingreceptacles to provide power from the first and second sources andconnecting the module to the power strip. The standard plug may beconnected to the module by plugging the standard plug into thereceptacle or may be indirectly connected.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a block diagram of an application for anauto-switching module of the present invention.

FIG. 2 illustrates an exemplary auto-switching module of the presentinvention.

FIG. 3 illustrates another exemplary auto-switching module of thepresent invention.

FIG. 4 illustrates another exemplary auto-switching module of thepresent invention.

FIG. 5A illustrates an application for the auto-switching module shownin FIG. 4.

FIG. 5B illustrates an application for an exemplary auto-switchingmodule.

FIG. 6 illustrates an application for the auto-switching module shown inFIG. 2.

FIG. 7 illustrates another application for the auto-switching moduleshown in FIG. 4.

FIG. 8 illustrates a schematic diagram for an exemplary auto-switchingmodule.

DETAILED DESCRIPTION

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and are herein described in detail. It shouldbe understood, however, that it is not intended to limit the inventionto the particular form disclosed, but rather, the invention is to coverall modifications, equivalents, and alternatives falling within thescope and spirit of the invention as defined by the claims.

FIG. 1 illustrates a block diagram of an application for anauto-switching duplex module 1 of the present invention. The module 1may be configured to match the form factor of a standard (e.g., NEMA orother electrical standard) duplex receptacle unit. That is, the module 1may be incorporated into a standard outlet box or may plug into astandard, outlet box. The module 1 may be coupled to one or moreelectronic devices (e.g., electronic devices 7, 9) that may each includea single power cord that terminates in a standard plug. The electronicdevices may be any electrically powered device, such as a criticalnetwork device, critical medical device, or other critical ornon-critical devices. The module 1 may include one or more standardreceptacles for receiving a standard plug of the electronic devices 7and 9. Further, the module 1 may be adapted to include terminalassemblies or wire-lead connections that permit coupling to a powersource 3 and a power source 5.

The module 1 may include logic for selectively interconnecting thestandard receptacles to the terminal assembly that is coupled to eitherthe power source 3 or the power source 5. In this regard, each standardreceptacle, and therefore each electronic device, is provided withaccess to alternate power sources for enhanced reliability. The logicfor selectively interconnecting the standard receptacles to the terminalassemblies may include a switch that is operable to automatically cycleupon the loss of power quality. That is, the switch may be operative forsensing a loss of power quality on one of the power sources (e.g., thepower source 3), and for switching a connection of the standardreceptacles in response to the loss of power quality.

FIG. 2 illustrates an auto-switching module 10 that is configured tomatch the form factor of a standard (e.g., NEMA or other electricalstandard) duplex receptacle unit. The housing 12 of the module 10 mayinclude terminal assemblies (e.g., plugs 16 and 18) that are configuredto plug into a standard duplex receptacle unit. The module 10 mayfurther include a standard receptacle 14 for receiving a standard plugfrom an electronically powered device (e.g., a network device, a medicaldevice, etc). Inside the housing 12, the electrical connection 24 of thereceptacle 14 may be selectively interconnected with the electricalconnections 20 and 22 of the plugs 16 and 18, respectively, via aswitching means 28 and an electrical connection 26. Although depicted asa single line, it should be readily understood that the electricalconnections 20, 22, 24, and 26 may generally comprise multipleelectrical conductors (e.g., line, neutral, ground wires, etc.).

In operation, the plugs 16 and 18 may be plugged into a standard-sizedduplex receptacle unit that is configured to provide power from a firstpower source (e.g., the power source 3 of FIG. 1) at a first receptacle,and a second power source (e.g., the power source 5 of FIG. 1) at asecond receptacle. In this manner, the module 10 may be operable toreceive power from one power source at plug 16, and to receive powerfrom another power source at plug 18. Further, an electronically powereddevice that has a single power cord that terminates in a standard plugmay be plugged into the module 10 at the standard receptacle 14.

The switching means 28 may be operable to couple the electricalconnection 26 between the electrical connection 24 of the receptacle 14and the electrical connection 20 of the plug 16 when there is sufficientpower available at plug 16 (e.g., there is no loss of power quality onthe power source coupled to the plug 16). The switching means 28 mayfurther be operable to sense a loss of power at the electricalconnection 20 (e.g., due to a loss of power quality from the powersource that is coupled to the plug 16), and to then automatically couplethe electrical connection 26 between the electrical connection 24 of thestandard receptacle 14 and the electrical connection 22 of the plug 18,which is coupled to a separate power source. In this manner, theelectronic device that is plugged into the receptacle 14 of the module10 may continue to receive power despite a loss of power quality at thepower source coupled to the plug 16. The switching means 28 may be anydevice that is suitable for this application. For example, as discussedbelow in relation to FIG. 3, the switching means 28 may comprise one ormore relay switches. Further, the switching means 28 may include one ormore solid-state devices. Those having skill in the art will readilyrecognize that various types of circuitry may be used to achieve thefunction of the switching means 28.

The switching means 28 may also be operable to sense a restoration ofpower at the plug 16, and further to switch the electrical connection 26back to the power source coupled to the plug 16 when the power hasreturned to an acceptable quality. In this configuration, the powersource coupled to the plug 16 may be designated as the primary powersource, while the power source coupled to the plug 18 may serve as asecondary power source. In another configuration, the switching means 28may be operable to sense the voltage level at both of the plugs 16 and18, and to only cycle when a loss of power quality occurs at the powersource that is then coupled to the receptacle 14. That is, in thisconfiguration, the power sources function as alternate sources, ratherthan primary and secondary power sources.

It should be appreciated that the electrical wiring that suppliesstandard wall duplex receptacles can easily be modified duringconstruction to supply the necessary separate branch circuits to themodule 10 (i.e., one branch circuit coupled to one of the receptacles ofthe duplex pair, and an alternate branch circuit coupled to thecomplementary receptacle of the duplex pair). Currently available duplexreceptacles are designed to allow electrical separation of each of thereceptacles of a duplex pair. Thus, retrofitting wired locations may beaccomplished by delivering the required branch circuits to desiredlocations and modifying the present configuration of the existing duplexreceptacle. In this regard, the modified traditional receptacle may thenbe used to supply the module 10 for its intended purpose.

FIG. 3 illustrates the module 10 shown in FIG. 2, wherein the switchingmeans 28 includes a relay 30. In operation, the relay 30 may be coupledto the electrical connection 20 via a conductor 32. The relay 30 may beoperable to couple the electrical connection 24 to the electricalconnection 20 via the electrical connection 26 by a control mechanismrepresented by the dashed line 34 when the voltage at the plug 16 isabove a predetermined threshold. That is, the voltage at the electricalconnection 20 may “energize” the relay 30 such that the controlmechanism 34 couples the connection 26 between the connections 20 and24. The relay 30 may further be operable to sense the voltage at theplug 16, and, in response to a loss of power quality, cycle theswitching means 28 by coupling the electrical connection 26 between theelectrical connections 22, 24. In this manner, an electrical device thatis plugged into the receptacle 14 will receive continuous power despitea loss of power quality at the power source that is coupled to the plug16. In other words, the electrical device will receive power from thepower source that is coupled to the plug 18 only when the power qualityfrom the power source coupled to the plug 16 is unacceptable.

FIG. 4 illustrates another embodiment of an auto-switching duplex module50. In this embodiment, the housing 52 of the module 50 includes twostandard receptacles 54 and 55 for receiving standard plugs fromelectronic devices that have power cords that terminate in standardplugs. Further, similar to the module 10 of FIG. 2, the housing 52 mayinclude standard plugs 56 and 58 that are configured to plug into astandard receptacle unit (e.g., NEMA or other electrical standard). Thereceptacles 54 and 55 may be coupled to an electrical connection 64,which may be selectively interconnected to alternate power sourcesthrough the switching means 68 and the electrical connections 60 and 62that are coupled to the plugs 56 and 58. In this regard, theauto-switching duplex module 50 provides for two electrical devices toreceive redundant power, which may enable higher reliability in manycontexts. Further, when coupled to a standard duplex receptacle, themodule 50 operates to maintain the receptacle count in the branchcircuit. That is, the designed per receptacle power density of thebranch circuit is preserved.

FIG. 5A illustrates an exemplary application for the auto-switchingmodule 50 shown in FIG. 4. As shown, the power cords 51 and 53 of twoelectrical devices (now shown) may be plugged into the standardreceptacles 54 and 55 of the housing 52 of the module 50. In turn, theplugs 56 and 58 of the module 50 may be plugged into standardreceptacles 72 and 74 of a standard duplex receptacle unit 70 (e.g.,NEMA or other electrical standard). The standard receptacle unit 70 mayinclude terminal assemblies 76 and 78 that are adapted to couple withtwo power sources 80 and 82. In this manner, two electrical devices thatterminate in a single standard plug may be provided with redundant powerthrough the auto-switching duplex module 50;

FIG. 5B illustrates an exemplary application for an auto-switchingduplex module 40. In this embodiment, the module 40 is incorporated intothe form factor of a standard duplex receptacle unit (e.g., NEMA orother electrical standard). In this regard, the power cords 51 and 53 oftwo electrical devices (not shown) may be plugged into the standardreceptacles 43 and 44 of the module 40. Further, the module 40 mayinclude terminal assemblies 41 and 42 for coupling to the power supplies80 and 82, respectively. In this configuration, two electrical devicesare provided with redundant power by connecting them with the module 40.Advantageously, the module 40 may be installed in any location where aconventional standard receptacle unit may be installed (e.g., a wall, arack, a power strip, etc.).

FIG. 6 illustrates an exemplary application for the auto-switchingmodule 10 shown in FIG. 2. In this application, the module 10 may becoupled to two power sources 95 and 96 through terminal assemblies 16and 18, which may be standard plugs or any other suitable couplingmechanism. Further, a standard receptacle unit (e.g., NEMA or otherelectrical standard) may be included between the module 10 and the powersources 95 and 96 to provide the coupling. A conventional power strip 90that includes a plurality of receptacles may be coupled to the module 10at the receptacle 14. The power strip 90 may include a power cord 92that terminates in a standard plug 94, so as to provide the necessarycoupling with the module 10. In this configuration, the module 10 servesto provide the plurality of receptacles of the power strip 90 withredundant power. As can be appreciated, multiple electrical devices maybe plugged into the power strip 90, and operated with redundant powersources 95 and 96.

FIG. 7 illustrates yet another exemplary application for theauto-switching duplex module 50 of FIG. 4. A shown, a power strip 100 isadapted to provide multiple sets of duplex receptacles (e.g., four setsof duplex receptacles). A first portion 106 (i.e., the top row ofreceptacles) of the power strip may include receptacles that are coupledto a power source 110 through a power cord 102 and a standard plug 103.Similarly, a second portion 108 (i.e., the bottom row of receptacles) ofthe power strip 100 may be coupled to a second power source 112 througha power cord 104 and a plug 105. Further, the auto-switching duplexmodule 50 may be plugged into the power strip 100, such that one plug ofthe module 50 is plugged into one receptacle of each of the portions 106and 108. In this manner, two electrical devices may be plugged into thereceptacles 54 and 55 of the module 50, and be provided with redundantpower from the power sources 110 and 112. As can be appreciated,multiple modules 50 may be plugged into the power strip 90 to provideadditional sources of redundant power. Furthermore, the auto-switchingmeans of the module 50 may be directly incorporated into the power strip90, so that the power strip 90 itself provides redundant power from thepower sources 110 and 112.

FIG. 8 illustrates a schematic diagram of another embodiment of anauto-switching module 150. The basic functionality of the module 150 isto facilitate the fast transfer of power delivered to a load powerconnection 172 between a primary power source connection 152 and analternate power source connection 154. For example, the module 150 maytransfer the power during a period that is less than about 15milliseconds, and preferably less than 10 milliseconds. Generally, themodule 150 operates to couple the primary power source connection 152 tothe load power connection 172 when the power at a primary power sourceis stable. Further, in response to a loss of power quality at the powersource coupled to the primary power source connection 152, the module150 is operable to couple the load power connection 172 to the alternatepower source connection 154 that is connected to an alternate powersource until power at the primary power source connection 152 isrestored. The module 150 may be operable to sense various power qualityfeatures on the primary power source connection 152, and to switch thepower connection in response to these features. The power qualityfeatures sensed by the module 150 may include interruptions,undervoltage, overvoltage, voltage fluctuations, frequency variations,or the like. The specific features and operation of the module 150 aredescribed in detail below.

The module 150 may include two single pole double throw (SPDT) relays166 and 168 to facilitate the transfer of power between the primarypower source connection 152 and the alternate power source connection154. As shown, the relay 166 couples the hot conductor 156 of theprimary power source connection 152 to the hot conductor 170 of the loadpower connection 172. The relay 166 also couples the hot node 158 of thealternate power source 154 with the hot conductor 170 of the load powerconnection 172. Similarly, the neutral conductors 157, 159 of theprimary power source connection 152 and the alternate power sourceconnection 154, respectively, are also coupled to the neutral conductor171 of the load power connection 172 through relay 168.

The module 150 also includes a third SPDT relay 164 that is positionedin the path of the primary power source connection 152. The relay 164serves to protect against an undesirable effect referred to herein as“arc carryover.” Arc carryover occurs when the current through thecontacts of a relay is great enough to allow an arc generated by thebreaking of a contact to which a load was previously connected tocontinue until the contact reaches the alternate source. This may resultin an effective short-circuit between two power sources, which undercertain conditions, may cause the current to increase rapidly, whichcould damage equipment or trip a circuit protection device, causingsystem downtime. One way to reduce the probability of arc carryover isto ensure a sufficient separation gap between the primary input relaycontact and the secondary relay contact. However, in space-limitedapplications, the size restrictions for the module 150 may preclude theuse of relays having a sufficient separation gap.

To reduce the probability of arc carryover, the relay 164 is introducedin the path of the primary power source connection 152 as a disconnectrelay. That is, the alternate pole of the relay 164 is unconnected. Therelay 164 functions in a timed relationship with the relays 166, 168 ina manner such that during a transfer sequence from one power source tothe other, the disconnect relay 164 disengages the primary power pathfrom the secondary power path during the short period when the transferrelays 166 and 168 change from one position to the other. By slightlyoffsetting the timing of the actions of the disconnect relay 164 fromthe switching action of the transfer relays 166 and 168, it can beassured that the AC power will pass through a zero current level duringthe transfer cycle. This, in conjunction with the addition of the thirdseparation gap provided by the relay 164, increases the arc suppressioncapacity of the module 150 significantly. To control the timing anddriving of the relays 164, 166, and 168, a Relay Driver andSynchronization section 184 is provided. The section 184 may includevarious analog and digital electronics to drive the relays 164, 166, and168. Driving the relays using electronics, as opposed to directactuation from the power sources, has advantages that are discussedbelow.

To further protect against arc carryover, a fuse or circuit breaker 162is positioned in the path of the alternate power source connection 154.It should be appreciated that a fuse or circuit breaker may be appliedin the path of the primary power source connection 152 in addition to,or instead of, the path of the alternate power source connection 154.The fuse or circuit breaker 162 may be a fast acting device that isoperable to open prior to the opening of a branch circuit breaker, whichmay prevent localized overload conditions from affecting other attachedequipment on the same branch circuit. In one embodiment, a 20 Apower-limiting fast-acting fuse is used, but other values or othercircuit protection devices may be substituted to provide the desiredprotection in various applications of the module 150. Further, thecircuit breaker 162 may be resettable.

The inventors have further recognized that it may be desirable tointroduce a delay when returning power from the alternate power sourceconnection 154 to the primary power source connection 152 following lossof power quality on the primary power source. In this regard, a delaymay help reduce the number of transitions in the event that the primarypower source is intermittent, or in a low or high voltage condition thatmay cause the relays to transfer back and forth unnecessarily. As anexample, a delay of three to five seconds may be introduced from thetime the primary power source is of acceptable quality to the time themodule 150 returns power from the alternate power source to the primarypower source. To provide this delay, a Voltage Sense and Return TransferDelay section 180 is provided. The section 180 is operable to sense thevoltage at the primary power source connection 152 via nodes 174 and175. Once the section 180 has determined that acceptable voltage at theprimary power source 152 has been available for a predetermined periodof time (e.g., 3 to 5 seconds), the section 180 provides a signal to theRelay Driver and Synchronization section 184. As shown, the sections180, 184 are coupled together by an optical isolator 182 that functionsto electrically isolate the primary power source connection 152 from thealternate power source connection 154. After receiving a signal from thesection 180, the Relay Driver and Synchronization section 184 may thenuse electronic control circuitry to activate the relays 164, 166, and168, which in turn returns power from the alternate power sourceconnection 154 to the primary power source connection 152. It should beappreciated that the sections 180 and 184 may include various digitaland/or analog components to achieve the voltage sensing and delayfunctions. For example, in one embodiment the section 180 includes adigital timer.

The use of electronic control circuitry by section 184 to drive therelays 164, 166, 168, instead of direct actuation by the primary powersource, may provide significant advantages. In previous embodiments, therelays are energized by the primary power source, such that the primarypower source remains connected to the load power connection when theprimary power source is stable. In the event of a loss of power qualityat the primary power source, the relays are not held, and thereforerelease, which in turn connects the load to the alternate power source.Upon return of power to the primary source, the relays immediatelyenergize, therefore reconnecting the load to the primary power source.As discussed above, this configuration does not allow for a delay to beintroduced when transferring from the alternative power source back tothe primary power source. Further, this configuration requires therelays to be energized the majority of the time (i.e., whenever theprimary power source is stable), causing unnecessary power consumptionand reduced relay life expectancy, which reduces the overall reliabilityof the module 150.

To solve the aforementioned problems, the relays 164, 166, 168 aredriven from the alternate power source connection 154. This isaccomplished by coupling the relay driver section 184 to the alternatepower source connection 154 through nodes 176 and 177. Therefore, thepreviously described electronic delay circuitry may now use theavailable alternate power source to operate from during the delayperiod. Further the relays 164, 166, and 168 may be energized onlyduring an outage period of the primary power source 152, which may be arelatively rare event. Therefore, this configuration may significantlyextend the probable life expectancy of the relays, reduce powerconsumption, and improve the overall reliability of the module 150. Forexample, in one embodiment, the average power dissipation of the module150 is less than about 200 milliwatts, and preferably less than about125 milliwatts.

Although not shown, it should be appreciated that various types ofcircuit protection devices (e.g., varistors, Zener diodes, etc.) may becoupled across the input or output conductors to limit voltage spikesdue to external or switching transients. Also, various types of linefilters may be included if necessary or desired.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, such illustration and description isto be considered as exemplary and not restrictive in character. Forexample, certain embodiments described hereinabove may be combinablewith other described embodiments and/or arranged in other ways (e.g.,process elements may be performed in other sequences). Accordingly, itshould be understood that only the preferred embodiment and variantsthereof have been shown and described and that all changes andmodifications that come within the spirit of the invention are desiredto be protected.

1. A power strip for use in delivering power to a plurality of devices,comprising: a first power cord for coupling with a first power source; asecond power cord for coupling with a second power source; a first setof receptacles electrically coupled with the first power cord; a secondset of receptacles electrically coupled with the second power cord; anda third set of receptacles electrically coupled with an auto-switchingmodule, the auto-switching module configured to sense a reduction ofpower quality from one of the first or second power sources and toselectively interconnect the third set of receptacles to either thefirst power cord or the second power cord responsive to the reduction ofpower quality.
 2. The power strip as set forth in claim 1, wherein theauto-switching module comprises a first plug for electrically couplingwith one of the first set of receptacles and a second plug forelectrically coupling with one of the second set of receptacles, suchthat selectively interconnecting the third set of receptacles to eitherthe first power cord or the second power cord responsive to thereduction of power quality comprises electrically coupling the third setof receptacles either to the one of the first set of receptacles via thefirst plug or to the one of the second set of receptacles via the secondplug.
 3. The power strip as set forth in claim 1, wherein the third setof receptacles is removably coupled with the first and second sets ofreceptacles via the auto-switching module.
 4. The power strip as setforth in claim 1, wherein the first set of receptacles is arranged in afirst row and the second set of receptacles is arranged in a second rowadjacent to the first row.
 5. The power strip as set forth in claim 1,wherein the first power cord terminates in a standard power plug forplugging into a standard receptacle.
 6. The power strip as set forth inclaim 1, wherein the first power cord and the second power cord aredisposed in a single power cable that terminates in two power plugs forplugging into two standard receptacles.
 7. The power strip as set forthin claim 1, further comprising: an arc carryover suppresser operable toforce an interrupt in current flowing into the third set of receptaclesduring a time when the auto-switching module is switching responsive tothe reduction of power quality.
 8. The power strip as set forth in claim1, wherein the first power source is mains line power.
 9. The powerstrip as set forth in claim 1, wherein the auto-switching module isconfigured to selectively interconnect the third set of receptacles toeither the first power cord or the second power cord responsive to thereduction of power quality after a predetermined period of time.
 10. Thepower strip as set forth in claim 1, wherein the auto-switching moduleis configured to switch interconnection of the third set of receptaclesfrom the first power cord to the second power cord responsive to thereduction of power quality in a period of time that is less than about15 milliseconds.
 11. The power strip as set forth in claim 1, whereinthe auto-switching module comprises one or more relays.
 12. The powerstrip as set forth in claim 1, wherein the auto-switching modulecomprises a timer.
 13. The power strip as set forth in claim 1, whereinthe auto-switching module comprises an optical isolation circuit forisolating the first and second power sources.
 14. The power strip as setforth in claim 1, wherein the power quality includes at least one ofinterruptions, undervoltage, overvoltage, voltage fluctuations, orfrequency variations.
 15. The power strip as set forth in claim 1,wherein the auto-switching module has an average power dissipation atfull load of less than about 5 watts.
 16. The power strip as set forthin claim 1, wherein the auto-switching module has an average powerdissipation at no load of less than about 200 milliwatts.
 17. The powerstrip as set forth in claim 1, wherein the reduction in power qualitycorresponds to a change in value of a parameter selected from the groupconsisting of: interruptions, under-voltage, over-voltage,under-current, over-current, voltage fluctuations, current fluctuations,and frequency variations.
 18. A method for use in delivering power to adevice having a power cord terminating in a standard plug, said methodcomprising the steps of: coupling a power strip electrically with afirst power source and a second power source, so that a first set ofreceptacles of the power strip is electrically coupled with the firstpower source, a second set of receptacles of the power strip iselectrically coupled with the second power source, and a third set ofreceptacles of the power strip is electrically coupled with the firstpower source via an auto-switching module; sensing a reduction in powerquality from the first power source using the auto-switching module; andswitching the third set of receptacles to be electrically coupled withthe second power source responsive to sensing the reduction in powerquality.
 19. The method as set forth in claim 18, further comprising:suppressing arc carryover during the step of switching the third set ofreceptacles to be electrically coupled with the second power source. 20.The method as set forth in claim 18, further comprising: coupling afirst plug of the auto-switching module electrically with one of thefirst set of receptacles so that the third set of receptacles iselectrically coupled with the first power source prior to the step ofswitching; and coupling a second plug of the auto-switching moduleelectrically with one of the second set of receptacles, whereinswitching the third set of receptacles to be electrically coupled withthe second power source responsive to sensing the reduction in powerquality comprises electrically coupling the third set of receptacleswith the second power source via the second plug subsequent to the stepof switching.